Motobecane Help Needed Badly!!!

I've just about had it with my '77 Motobecane 50L. After replacing just about everything on that bike, it still won't run. Here's the scoop:

I replaced the piston & rings. I now have over 150 pounds of compression. The coil is new and the points were replaced and set to .015. I have a big fat white/blue spark. The carb works perfectly and fuel is getting to engine. The muffler and exhaust port are both free of carbon. I have spark, compression and fuel, what the hec else is there? Other than setting the points, can a Motobecane engine be timed?

When I try to pedal start the engine, all I get are engine popping noises and backfiring. I don't know what else to do. If I can't get my Moby running soon, I'm gonna sell it. I love the bike, but even I have my limits. I can't afford to spend any more time or money on this bike.

If any Motobecane expert out there could impart some wisdom on me, I would be most thankful.



Re: Motobecane Help Needed Badly!!!

it sounds like the timeing because of the poping try this way to set the points ok

To set the timing:

1. Remove the flywheel cover.

2. On the flywheel you'll notice two marks, a T and an F.

3. On the engine near the flywheel there should be a notch that lines up with the T and F as they spin past.

4. The T means "top dead center" when it passes the notch.

5. The F means "fire" when it passes the notch. As the F passes the notch, the points should just be opening.

6. Use a cigarette rolling paper to set your timing. Back up the flywheel so that it is before the F mark. Pry open the points, and stick a piece of rolling paper between the points. You can do this without removing your flywheel.

7. Keep a light tension on the paper with one hand as you slowly rotate the flywheel forward. When the points begin to open they will release the cigarette paper. If the paper is released exactly as the F mark passes the notch in the crankcase then your timing is correct. If it isn't, adjust your points until they open at the correct time.

8. To adjust points, loosen the flathead screw on the points about a quarter to a half turn --you don't want to over loosen it or the points won't stay set. Adjust the points open or closed and retest. Tighten the screw when you are done.

Re: Motobecane Help Needed Badly!!!

it 4 a honda but it might work

Re: Motobecane Help Needed Badly!!!

There are no "T" or "f" marks on the flywheel that i can find.


Re: Motobecane Help Needed Badly!!!

ok then im lost

look at the attchment.


Re: Motobecane Help Needed Badly!!!

A Motobecane flywheel looks nothing like that. Once you remove the magneto cover, the points, condensor, etc are all exposed.

Re: Motobecane Help Needed Badly!!!

o well i dont no then i will try and find out 4 you

Re: Motobecane Help Needed Badly!!!

is it a 2 or 4 stroke

Re: Motobecane Help Needed Badly!!!

is this what your moter looks like

look at attachment


Re: Motobecane Help Needed Badly!!!

Mine's a 50L, but yes, that's the motor.

Re: Motobecane Help Needed Badly!!!

ok find to dead center. Back off the nut so the poits close right before the piston hits top dead center, Umay have a short. Also make sure you put the magneto magnet cover on right

Re: Motobecane Help Needed Badly!!!

I did that and the points don't open until you back it up to the bottom of the stroke. It appears to be 180 degrees out.


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